What is Reverse DNS?

出典: くみこみックス

Reverse DNS (Domain Name Technique) lookup, also known by the acronym (rDNS), is the method by which someone can appear up a host name given a specific clergy shirt IP address. Reverse DNS is also recognized in some locations as reverse resolving. It is the opposite of DNS lookup, by which an individual looks up an IP address given a distinct host name.

Why use Reverse DNS?

A reverse DNS lookup is normally performed for troubleshooting purposes. Commonly, tools like a traceroute or a ping will do a reverse DNS lookup to figure out the flow of site visitors from 1 point to one more. Yet another widespread spot for reverse DNS lookup is when accessing a persons e-mail. Many modern email providers will do reverse DNS lookups to figure out if an e mail was sent from a identified spam address. Ultimately, reverse DNS can be utilised to make sure that there is a suitable relationship between the owner of a server and the owner of a domain name. This technique, known as Forward Confirmed reverse DNS (FCrDNS) is utilized to place a cease to phishing websites a guide to church statues and spammers.

What is IPv4 Reverse DNS lookup?

IPv4 Reverse DNS is a type of reverse DNS that makes use of a reverse IN-ADDR entry with the unique domain in-addr.arpa. The IP address represented in the in-addr.arpa domain is written in reverse order to the usual way that the IP address is written. For instance, if a individual was performing a reverse domain lookup for an address such as 192.168.1.1, he would do the lookup making use of 1.1.168.192.in-addr.arpa.

What is IPv6 Reverse DNS lookup?

IPv6 Reverse DNS lookup is a type of reverse DNS that uses the particular domain ip6.arpa. Unlike IPv4 Reverse DNS lookup, IPv6 Reverse DNS lookup does not use the regular IP address style of hunting up host names. Rather, it makes use of a sequence of nibbles, or four bit aggregations, in reverse order with every single quantity separated by a period. For example, if a individual was performing a reverse domain lookup for an address such as 2001:0db8:::::1428:57ab he would do the lookup using b.a.7.5.8.two.4.1.....8.b.d..1...2.ip6.arpa.

What takes place when there are many host names assigned to one particular IP address?

A reverse DNS lookup will be in a position to establish all of the host names linked with a distinct IP address, even though this practice is occasionally frowned upon. Numerous low-cost internet hosting plans will offer you shared virtual hosts exactly where several internet sites share space on the identical IP address. Despite the fact that this does not influence the validity of the information returned by a reverse DNS lookup, it can san diego warrants lead to issues with other services.